It has heretofore been proposed to compress a helically coiled spring and to then permit the spring to expand while pushing a plunger within a cylinder, so that lubricant is dispensed from the cylinder under pressure to a bearing. Exemplary of such devices are those disclosed in the following U.S. Pat. Nos.:
1,489,999 to Gallipoli of Apr. 8, 1924 PA0 3,393,846 to Sundholm of July 23, 1968 PA0 1,676,358 to Schott of July 10, 1928 PA0 2,925,147 to Minera of Feb. 16, 1960 PA0 3,780,830 to Helgerud of Dec. 25, 1973 PA0 3,595,340 to Obergefell, July 27, 1971
In an early U.S. Pat. No. 881,896 to Brown of Mar. 17, 1908, a windmill oiler is disclosed, in which a tension spring applies pressure on the piston head by pulling thereon, instead of the conventional pushing on the piston head as in the above patents.
It has also been proposed to provide a single, substantially constant-pressure, coiled bandspring, immersed in the hydraulic fluid charge in a cylinder, to apply a constant pressure on a rolling diaphragm type piston as in U.S. Pat. No. 3,581,774 to Oeland, Jr., et al of June 1, 1971.
A pair of back-to-back constant force springs are disclosed in U.S. Pat. No. 2,635,282 to Trammell of Apr. 21, 1953 detachably connected to one side of a window sash by hooks.